Investigation of disordered oxygen vacancies and coordination environment around Y, Bi and Se in YBi2O3.5+0.5xSe1-xClx

Our research programme involves development of the next generation of layered materials for thermoelectric applications. YBi2O3.5+0.5xSe1-xClx (x=0,0.3,0.5,0.7) was synthesized through a systematic computational and experimental investigation involving the prediction of stable layered compounds.Previous neutron diffraction data predicted oxygen vacancies in the material. Our recent DFT calculations have suggested that these oxygen vacancies should have strong local order, with a preference for Y being seven coordinates.We aim to determine the oxygen vacancies which should have strong local order, with a preference for Y being seven coordinates. The preliminary calculation suggested that oxygen vacancies might be disordered due to distortion in the structure. By measuring the total scattering at room temperature, we will see can detailed information about the distribution of these oxygen vacancies and how they influence the local structure, allowing us to understand the coordination environment around yttrium (Y), bismuth (Bi), oxygen (O), and selenium (Se) , providing details on how these atoms are arranged locally, even if the bulk structure is well-defined or disordered.